Let x be the size of a house sq ft and y be the amount of na

Let x be the size of a house (sq ft) and y be the amount of natural gas used (therms) during a specified period. Suppose that for a sample from a particular community, x and y are related according to the simple linear regression model with b1 = 0.017, and b0 = -5.0.

Would you use the model to predict mean usage for a 500 square foot house? Why or why not? (Note: There are no small houses in the community in which this sample was taken.)

Solution

No. 500 sq. ft. is quite a small house. The sample used to obtain these coefficients is for bigger houses, so 500 sq. ft. is not within the range of the sample.

Thus, the model cannot be used.